In an indoor positioning system, the location of a wireless device such as a mobile user terminal can be determined with respect to a location network comprising multiple wireless reference nodes whose locations are known, typically being recorded in a location database which can be queried to look up the location of a node. These wireless nodes may be referred to as anchor nodes. Measurements are taken of the signals transmitted between the mobile device and a plurality of anchor nodes (typically RF signals), for instance the RSSI (receiver signal strength indicator), ToA (time of arrival) and/or AoA (angle of arrival) of the respective signal. Given such a measurement from three or more nodes, the location of the mobile terminal may then be determined relative to the location network using techniques such as trilateration, multilateration, triangulation, and/or a fingerprint based technique (comparing the current measurements to a “fingerprint” of previously sampled measurements taken at known locations throughout the environment). Given the relative location of the mobile terminal and the known locations of the anchor nodes, this in turn allows the location of the mobile device to be determined in more absolute terms, e.g. relative to the globe or a map or floorplan.
As well as indoor positioning, other types of positioning system are also known, such as GPS or other satellite-based positioning systems in which a network of satellites act as the reference nodes. Given signal measurements from a plurality of satellites and knowledge of those satellites' positions, the location of the mobile device may be determined based on similar principles.
US20140106735 discloses methods and systems in which a portable electronic device communicates with an external device to determine a location. Upon determining its location, the portable electronic device transmits this information as well as identifying information to a control processor. The control processor controls one or more controllable devices according to the location and identifying information. The portable electronic device may determine the location via NFC tag or via one or more RF beacons transmitting information according to the Bluetooth 4.0 protocol.
The determination of the device's location may be performed according to a “device-centric” approach or a “network-centric” approach. According to a device centric approach, each reference node emits a respective signal which may be referred to as a beacon or beaconing signal. The mobile device takes measurements of signals it receives from the anchor nodes, obtains the locations of those nodes from the location server, and performs the calculation to determine its own location at the mobile device itself. According to a network-centric approach on the other hand, the anchor nodes are used to take measurements of signals received from the mobile device, and an element of the network such as the location server performs the calculation to determine the mobile device's location. Hybrid or “assisted” approaches are also possible, e.g. where the mobile device takes the raw measurements but forwards them to the location server to calculate its location.
Based on information about user position in an indoor environment, a variety of location-based services may be offered. One application of a positioning system is to automatically provide a wireless mobile device with access to control of a utility such as a lighting system, on condition that the mobile device is found to be located in a particular spatial region or zone associated with the lighting or other utility. For instance, access to control of the lighting in a room may be provided to a wireless user device on condition that the device is found to be located within that room and requests access. Once a wireless user device has been located and determined to be within a valid region, control access is provided to that device via a lighting control network.
There is a trend toward greater connectivity and intelligence in lighting systems. Thus, wirelessly-networked lighting systems will play an important role with a desire for easier commissioning and control of lighting systems. A consequence will be a dense deployment of anchor nodes, e.g. one wireless node per lamp or a wireless node for a group of lamps in a room.